Furnace



Dec. 8, 1936. .1. o. BETTERTON FURNACE Original Filed Jan. 50, 1933Patented Dec. 8, 1936 UNITED STATES PATENT OFFICE FURNACE Jesse 0.Betterton, Metuchen, N. J., assignor to American Smelting and RefiningCompany, New York, N. Y., a corporation of New Jersey Originalapplication January 30, 1933, Serial No. 654,176. Divided and thisapplication July 25,

1934, Serial No. 736,894

4 Claims. (01. 26619) '5 high state of purity and possessing anexcellent white color tone.

By the present invention white antimony oxide free from lead or at mostcontaining only insignificant or permissible amounts of that. element isvolatilized directly from antimony-lead alloys having a lead contentwithin the range of ap-' preciable quantities to approximately 60%.

In general, the invention contemplates establishing an active, thin,molten, mobile slag film, oil-like in appearance, upon the surface of amolten antimony-lead bath in the presence of a suitable oxidizingatmosphere and so stabilizing the system that practically pure white,leadfree antimony oxide is volatilized from the supernatant slag filmregardless of the concentration of lead in the bath within the limitsheretofore specified.

Among other features the invention provides an apparatus in which theindicated operations may be carried out, which apparatus is adapted forready manipulation and is of a high degree of simplicity ofconstruction.

The present application is a division of application Serial No. 654,176,filed January 30, 1933 which issued as Patent No. 2,035,454 on MarchAlthough the novel features which are believed to be characteristic ofthis invention will be particularly pointed out; in the claims appendedhereto, the invention itself, as to its objects and advantages, and themanner in which it may be carried out, may be better understood byreferring to the following description taken in connection with theaccompanying drawing forming a part thereof, and in which Fig. 1 is anelevation of one type of apparatus suitable for practicing the method ofthe invention;

Fig. 2 is an elevation taken along the line 2-2 of Fig. 1 and at rightangles to the elevation of Fig. 1.

Referring more particularly to the drawing, it will be seen that theillustrated form of furnace assembly comprises a steel casing I linedwith suitable refractory material 2 with beams 3 supporting a cast ironmelt and fuming pot 4. The furnace is mounted on trunnions 5 and may betilted by suitable manipulation of the worm gear 6. A burner 1, openinginto heating chamher 8 is provided for heating the antimony-lead bath 9in fuming pot 4 while flue Ill provides an exit for waste combustiongases. A hood ll, adapted to fit snugly over fuming pot 4 is providedwith adjustable ventilators l2 and an inner cylinder I3, the purpose ofthis cylinder 6 being to control the velocity of the air passing overthe surface of the bath 9, the velocity of the air increasing as thecylinder I3 is lowered towards the bath and decreasing as the cylinderis raised. The cylinder I3 is capable of adjust- 10 ment both in respectto hood II and the surface of the bath 9 by suitable means (not shown)attached to chains M. A flue l5 leads from hood H to suitable fumerecovery apparatus (not shown) employing the above described apparatus.5

The production of antimony oxide possessing the desired improvedproperties may be carried out as follows:

The furnace is brought to the upright position and suitableantimony-bearing material, for ex- 20 ample, antimony dross containingover 40% antimony and the balance substantially lead, is charged to thepot 4. The metal may be melted and brought to a suitable temperature byheat derived from burner I and any dross formed 25 during the meltingdown operation removed from the molten bath. Hood ll may then be loweredover the fuming pot and the inner cylinder l3 adjusted so that the loweredge is a suitable distance, for instance, approximately 9", above the30 surface of the bath, and the desired distance may be mainta ned bysuitable readjustment as the metal level falls during the operation ofthe process due to depletion of the antimony content of the bath byvolatilizatlon of antimony oxide. 35

Upon removal of the melting down dross and exposure of the clean moltenmetal to the atmosphere, a very thin oil-like mobile slag film forms onthe surface of the bath 9 and antimony oxide, white in color andpractically free from 40 lead, rapidly volatilizes. As a thin hardcrust. appears on the slag film after a time which will depress thevolatilization of antimony oxide if the crust is allowed to accumulate,the slag film is gently worked from time to time, for example, 45 by aniron tool, in order to maintain the thin, molten, mobile slag film andto prevent and break up crust formation. When necessary the surfaceshould be skimmed with a perforated skimming tool or other suitabledevice to remove accumulated crust from the system. The metal should bemaintained within a controlled temperature range, for instance,approximately 1375 F. to 1500 F., and air admitted in required andregulated amounts through vents l2 in hood 55 H, care being taken toprevent rupturing the surface of the slag film or appreciable coolingthereof by the incoming air.

By thus maintaining conditions of equilibrium between the molten bath,the thin slag film and the oxidizing atmosphere, fuming of practicallypure antimony oxide may be effected until the antimony content of thebath is depleted to approximately antimony.

The fume as it arises from the kettle may be conducted out through theinner cylinder l3 of hood H to suitable recovery apparatus, for example,a baghouse, afan (not shown) preferably being utilized in thisoperation.

When the fuming operation is completed, for example, when the antimonycontent of the bath falls below 40% the heat may be turned off, theburner I moved out of the way, the hood H raised and the kettle emptiedby suitably operating the worm gear 6 to tilt the furnace. Thereafterthe furnace may be brought back to its original position, additionalantimony bearing material charged to the pot 4 and the operationrepeated.

It will be noted that the hood H is made of two portions or sections,one of these being of substantially uniform diameter, the other flaringoutwardly to fit over the rim of the receptacle or kettle 4. The slopeof the flaring portion of the hood is such that the air inlet vents l2will direct air directly onto the surface of the bath 9, so that thesurface will be swept by the air currents thus admitted. The portion ofthe hood which is of uniform diameter serves as a guide for theadjustable member I3 during movement thereof, assuring properpositioning thereof relative to the bath 9.

It is to be clearly understood that the preceding specific example isgiven merely for the purpose of illustration and is in no sense to beconstrued as limiting the broad scope of the invention; and it will beunderstood therefore that it is intended and desired to embrace withinthe scope of this invention such modifications and changes as may benecessary to adapt it to varying conditions and uses.

What is claimed is:

1. A volatilization furnace comprising the combination with a casing, ofa melting and fuming kettle mounted in the casing adapted to receive acharge and to enable the surface of the charge to be swept with air,means for heating the kettle to melt the charge therein, a hood fittingover the kettle in close relationthereto and enclosing the rim thereof,the said hood having an upwardly converging portion adjacent to thekettle and a flue communicating therewith, air intakes in the upwardlyconverging portion of the hood positioned to direct sweeping currents ofair onto the surface of the charge in the kettle to promote fuming ofvolatile oxide products from the charge and to carry the said productsthrough the flue, and adjustable means for controlling the air intakesfor regulating the amount of air sweeping the charge in the kettle atany given time.

2. A volatilization furnace comprising the combination with a casing, ofa melting and fuming receptacle mounted in the casing adapted to receivea charge and to enable the surface of the charge to be swept with air,means for heating the receptacle for melting the charge therein, a hoodfitting over the receptacle in close relation thereto and enclosing therim of the receptacle, adjustable ventilators in the hood for admittingcurrents of air directly to the charge for sweeping over the surface ofthe charge for oxidizing the same and to promote fuming of volatileoxide products from the surface of the charge, an adjustabledraft-controlling member positioned in the hood and adapted to bepositioned at variable distances above the charge for regulating thedraft of air contacting with the charge, and means for adjusting theheight of the draft-controlling member above the charge.

3. A volatilization furnace comprising the combination with a casing, ofa melting and fuming kettle mounted in the casing adapted to receive acharge and to enable the surface of the charge to be swept with air,means for heating the kettle to melt the charge therein, a hood fittingover the kettle in' close relation thereto and enclosing the rimthereof, air intakes in the hood positioned to admit sweeping currentsof air directly over the surface of the charge in the kettle to promotefuming of volatile oxide products from the charge, said air intakeshaving adjustable means for controlling the amounts of air passing overthe charge.

4. A volatilization furnace comprising the combination with a casing, ofa melting and fuming kettle mounted in the casing adapted to receive acharge and to enable the surface of the charge to be swept with air,means for heating the kettle to melt the charge therein, a hood fittingover the kettle in close relation thereto and enclosing the rim thereof,the said hood having an upwardly converging portion terminating in aportion of approximately uniform cross-section and a flue communicatingtherewith, air intakes in the converging portion of the hood positionedto direct sweeping currents of air onto the surface of the charge in thekettle to promote fuming of volatile oxide products from the charge andto carry the said products through the flue, an adjustabledraft-controlling member movably suspended in the hood and adapted to beadjustably positioned at variable distances above the charge forcontrolling the draft of air contacting with the charge, means foroperating the draft-controlling member of raising and lowering the samerelatively to the charge, the said portion of the hood of uniformcross-section serving to guide the draft-controlling member duringadjustment thereof relatively to the charge and means associated withthe flue for collecting fumed products.

. JESSE O. BETTERTON.

